1. Field of the Invention
The present invention relates to a method of testing electrical characteristics with a probe device.
2. Description of the Prior Art
In recent years, techniques are being completed for manufacturing large liquid crystal boards (hereinafter referred to as LCDs (Liquid Charged Devices)), each constituting a television screen or the like. Further, a mass-production of LCDs is developing rapidly. But, it is desired that a probe device for testing electrical characteristics of mass-produced LCDs be developed.
LCD electrical characteristics are conventionally tested using a probe card or a tester. However, strong demand has arisen for testing LCD electrical characteristics under severe conditions upon radiation of external light on an LCD.
A visible condition of an image displayed on the screen of an LCD is greatly changed due to a state of light emitted thereon. In other words, the LCD cannot be tested whether to be normal without light radiation on the LCD.
However, no conventional methods are available to test the LCD electrical characteristics with light radiation on the LCD. In order to test the LCD electrical characteristics under severe conditions (i.e., light radiation on the LCD) and LCD is mounted in a jig and is energized. External light is then incident on the LCD, and the LCD is tested whether to be normal by observation with a naked eye.
It is possible to test LCD electrical characteristics under severe conditions with light radiation if a light source is arranged in a test unit of a probe device. However, heat is dissipated from the light source to disturb a temperature atmosphere inside the test unit. In addition, a space is required in the test unit to receive the light source. Furthermore, various problems are posed in practical applications.